
theorem Th14:
  for V being RealUnitarySpace, W1,W2 being Subspace of V holds W1
  /\ W2 = W2 /\ W1
proof
  let V be RealUnitarySpace;
  let W1,W2 be Subspace of V;
  the carrier of W1 /\ W2 = (the carrier of W2) /\ (the carrier of W1) by Def2;
  hence thesis by Def2;
end;
